Gels are soft materials comprised of two coexisting phases: a solid component (gelator) that immobilizes a fluid component by surface tension. The gelator molecules can self-assemble to span the entire sample in a continuous, cross-linked network. In contrast to chemical gels where the gelator is covalently linked through the entire system, physical gels interact non-covalently and can form reversible gels. The introduction of metal to the gelator provides alternative binding sites to design and construct complex network architectures. The diverse metal-ligand coordination environments that induce the self-assembly process influence gel properties. The resulting “metallogels” have garnered ever-increasing interest in the fields of coordination polymer gels and supramolecular polymer gels. Metallogels are highly versatile materials with a wide range of applications in sensors, nanodevices, drug delivery, catalysis, and cosmetics.
Coinage metals (e.g., Cu, Ag, and Au) react with thiols to form straight-chain polymers of 1:1 M(I):SR stoichiometry. These complexes are precursors for functional materials including metal nanoparticles and supramolecular hydrogels. In various supramolecular hydrogels, metallophilic interactions drive self-assembly into two-dimensional (2D) sheets that stack in the third dimension to form lamellar structures. These gels are currently studied for their potential applications in medicine, adhesives, and sensing. However, current metallogels require various additives to regenerate after dehydration. The development of a reversible metallogel that could be regenerated with only water would provide a broad range of additional applications and advantages.